In the art of automobile braking systems, it is common now to provide dual systems so that a brake failure will only be partial, rather than complete. Of course, this affords only partial braking effectiveness. Of course, failure of the seals may result in complete failure of the hydraulic braking system. Also there are provided separate mechanical parking or emergency brake systems, which may slightly impede or delay emergency actuation. Also, a wide variety of automatically operable backup systems have been proposed, but these have not been found satisfactory and have not met with wide acceptance. Applicant is aware of the below listed prior patents:
______________________________________ U.S. PAT. NO. PATENTEE ______________________________________ 2,116,882 DICKEY 3,333,902 LIVERANCE ET AL. 3,424,281 KAWABE ET AL. 3,436,126 MOUSLEY 3,582,150 WILLIAMS 3,650,568 POPLAWSKI 3,858,944 POCOBELLO ET AL. ______________________________________